Updated phase II study results of OPAXIO in patients with advanced esophageal cancer

Cell Therapeutics, Inc.Jun 7 2010

Cell Therapeutics, Inc. ("CTI") (Nasdaq and MTA: CTIC) announced today that updated phase II study results of OPAXIO (paclitaxel poliglumex) in patients with advanced esophageal cancer demonstrated that 38% (15/40) patients receiving OPAXIO in combination with cisplatin and concurrent radiation achieved a pathologic or endoscopic complete response.  A pathological complete response, observed in 32% of patients, is recorded only when the esophagus is surgically removed after therapy and no tumor can be found microscopically.  In historical studies, pathologic complete response has correlated with prolonged survival.  Pathologic complete response rates with the current U.S. standard regimen of 5FU + cisplatin chemotherapy with concurrent radiation for patients with esophageal cancer are approximately 15% with 40% of patients experiencing severe (grade 3-4) inflammation and ulcers in the esophagus and stomach necessitating tube feeding. The results were presented by Kimberly Perez, M.D., Warren Alpert School of Medicine, Brown University, at the American Society of Clinical Oncology Annual Meeting in Chicago, Illinois. CTI plans to meet with the U.S. Food and Drug Administration ("FDA") in the second half of 2010 to explore a potential phase III registration study based on these results.

"OPAXIO significantly improved the pathologic complete response rate that has been shown in previous phase III trials using standard chemotherapy plus radiation," said Dr. Perez. "Importantly, we did not see the severe regional side effects associated in treating patients with platinum, 5-FU, and radiation based regimens with only one patient requiring a feeding tube in this study. Typical rates of grade 3-4 esophagitis for this regimen are on the order of 40%."

The phase II study enrolled 40 patients with pathologically-confirmed, locally-advanced adenocarcinoma or squamous cell carcinoma of the esophagus or gastro-esophageal junction with no evidence of distant metastisis.  The patients received weekly paclitaxel poliglumex (50mg/m2) and cisplatin (25mg/m2) for six weeks with concurrent 50.5Gy of radiation. The updated data demonstrated that of the 37 patients who underwent surgery, 12 patients achieved a pathologic complete response.  Additionally, three patients achieved a complete clinical endoscopic response and refused surgery.  Importantly, only one patient required a feeding tube and one patient used total parenteral nutrition. There were no grade 4 hematologic adverse events. Grade 3 hematologic adverse events included neutropenia (6%) and grade 3 non-hematologic toxicities included nausea (8%), esophagitis (6%), allergy (6%) and fatigue (3%).

"The high pathologic complete response rate coupled with tolerability confirms the striking efficacy of OPAXIO as a tumor-specific radiosensitizer in preclinical studies (Milas et al.; Int J Radiation Oncol Biol. Biophys, 55:2-7-12, 2003) and the previous phase I study of OPAXIO and radiation in locally advanced esophageal and gastric cancer (Dipetrello et al.: American Journal of Clinical Oncology: 29:376-379, 2006)," said Jack Singer, M.D., Chief Medical Officer of CTI. "The important features of the current study are both the higher than historical pathological response rate, a potential excellent surrogate for long-term survival, and the dramatically lower side effects than would be expected from conventional neoadjuvant chemoradiotherapy with cisplatin and 5-FU."